Eggleton added that invoking the clause is "most regrettable, most appalling."

The former mayors spoke in support of city councillor Kristyn Wong-Tam's campaign launch event. Wong-Tam, seeking her third term as Ward 27 councllor, has been among the most vocal critics at council over the province's decision.

Wong-Tam has been among the most vocal opponents of Premier Doug Ford's plan to invoke the notwithstanding clause. (Adrian Cheung/CBC News)

Crombie echoed concerns over the power of the province to overrule court decisions.

"We live in a world, yes, of elections. But also of rule of law."

Eggleton, who served as mayor for 11 years, said he could not remember the same kind of tension between city and province, no matter which way the political winds blew.

Ontario Premier Doug Ford has vowed to use the notwithstanding clause to push through his legislation that would cut the size of Toronto city council nearly in half. (Christopher Katsarov/Canadian Press)

"During my time as mayor, there were three different governments and three different persuasions ... I got along with all of them and I thought all of them were trying to do what was best for Toronto," Eggleton said.

The Ontario Legislature is set to meet on Wednesday to vote on the revised bill. Premier Ford has said the process will be a free vote.

City councillors will meet on Thursday for a meeting to discuss what actions may be taken on their end.